The invention concerns an electric multilayered component with a stack of layers, which include superimposed dielectric layers that cover a ceramic material and electro-conductive electrode layers lying between them. Beyond that, the invention concerns a method for producing the multilayered component.
In patent DE 197 19 174 A1, a component of the above type is known where the electric resistance of the dielectric layers exhibits a positive temperature coefficient and where the electrode layers are produced from aluminum. To produce such a multilayered PTC resistor, the use of base metal for an electrode layer is necessary, because only such metals form, for the purpose of a PTC element, a necessary oxide layer on their surfaces. This oxide layer is required for the barrier, which is a layer that may be dismantled, between the electrode and dielectric layers.
The known component has the disadvantage that aluminum used for PTC resistor ceramic is not stable and oxidizes at typical sinter temperatures >1300° C. The electrode layers therefore exhibit a high ohm resistance due to the sinter that is undesirable for a multilayer PTC resistor.
Furthermore, the known PTC component has the disadvantage that aluminum is easily diffused into the ceramic at the highest sinter temperatures of >1000° C. and impairs the desired characteristics of the PTC ceramic.
Moreover, the elements of the aforementioned method are known from patent DE 199 16 380 A1 where the dielectric layers are selected from a piezoelectric material. The electrode layers are produced from a mixture of silver and palladium
These known components have the disadvantage that the materials, silver and palladium, are expensive to obtain. More easily and cheaply available materials, such as copper, require a very high, process-technical method in order to oxidize the copper.